This invention relates generally to rotating dome-shaped structures and more particularly to spinners used in high bypass ratio turbofan engines.
Numerous applications exist for turbomachinery, such as gas turbine engines used to propel a variety of aircraft. One such gas turbine engine is the high bypass ratio turbofan engine, which includes a large, ducted fan usually placed at the front of the engine. The fan serves to produce greater thrust and reduce specific fuel consumption. Typically, the fan in a high bypass ratio turbofan engine includes a fan hub or disk drivingly connected to a shaft driven by the engine""s low pressure turbine, and a number of fan blades mounted to the disk. A dome-shaped member, known as a spinner, is attached to the front of the fan disk to provide an aerodynamic flow path for air entering the fan. Given its location at the front of the engine, the spinner is susceptible to being struck by foreign objects during flight. Accordingly, spinners must be capable of withstanding such impacts while contributing minimal additional weight to the engine.
To accomplish this, conventional spinners are made from materials having high strength-to-weight ratios, such as aluminum. Laminated composite materials have also been suggested for spinner applications. However, conventional laminated composites have lower interlaminar shear strength and impact resistance capability than metal. When a foreign object strikes a laminated composite spinner, the composite layers tend to delaminate along the resin matrix. In order to improve impact resistance, the composite structure must be designed to be thicker than a metal counterpart. The result is that the weight advantage of using the composite material will be diminished and the cost of making the thicker structure can become prohibitive.
The same problems exist for spinners or other rotating dome members used in applications other than high bypass ratio turbofan engines. Examples include propeller spinners in turboprop engines, the spinner or fairing on top of a helicopter rotor, and similar structure found in marine engines.
Accordingly, there is a need for an improved spinner to resolve the problems associated with prior spinners and thereby provide increased impact resistance capability in a cost and weight efficient manner.
The above-mentioned need is met by the present invention which provides a spinner made of a three dimensional orthogonal woven composite material The spinner defines a generally conical shell having a plurality of axial rib stiffeners and at least one circumferential rib stiffener integrally formed thereon.
The present invention and its advantages over the prior art will become apparent upon reading the following detailed description and the appended claims with reference to the accompanying drawings.